<!DOCTYPE html>
<html>
<head>
<style>
table {
    border-collapse: collapse;
    border: 5px solid yellow;
}
td {
    border: 1px solid red;
    padding: 16px;
    width: 32px;
    height: 32px;
}
td.cell5 {
    border: 30px solid blue;
}
td.cell6 {
    border: 5px solid green;
}
</style>
</head>
<body>
<table>
<tr id="row1">
    <td> 1
    <td> 2
    <td> 3
</tr>
<tr id="row2">
    <td> 4
    <td class="cell5"> 5
    <td class="cell6"> 6
</tr>
<tr id="row3">
    <td> 7
    <td> 8
    <td> 9
</tr>
<tr id="row4">
    <td> 10
    <td> 11
    <td> 12
</tr>
<tr id="row5">
    <td> 13
    <td> 14
    <td> 15
</tr>
</table>

</body>
</html>

